1. Field of the Invention
The present invention relates to a machining monitor for a wire electric discharge machine.
2. Description of the Related Art
A wire electric discharge machine feeds an electrode wire in the axial direction thereof, moves a workpiece relative to the electrode wire in a direction approximately perpendicular to the axial direction, and applies voltage pulses between the electrode wire and workpiece while directing machining fluid from a nozzle toward the portion to be machined, thereby machining the workpiece by electrical discharge.
One type of wire electric discharge machine has a numerical control device; a numerical control (NC) program generating apparatus is used to create an NC program for machining the workpiece to a prescribed shape, and the workpiece is machined by using the NC program to drive the numerical control device.
The NC program generating apparatus has depicting functions for depicting the shape of the workpiece. NC program generation is assisted by using these depicting functions to display the workpiece shape on a screen. FIG. 11A shows an exemplary drawing depicted by an NC program generating apparatus.
Some wire electric discharge machines have functions for displaying actual machining traces on a display screen. In the configuration shown in FIG. 12A, a personal computer (PC) 110 and an NC controller 121 are interconnected by a bidirectional signal line so that the PC can be used for monitoring purposes. Machining data is created on the PC 110 and operational status is output from the NC controller 121 in the form of M codes or the like, enabling the PC 110 to monitor the statuses of the machining apparatus 120 and NC controller 121. FIG. 11B shows an exemplary drawing depicted by a wire electric discharge machine.
As described above, the NC program generating apparatus displays only the workpiece shape and the wire electric discharge machine displays only the machining trace; they are not designed to relate the workpiece shape to the actual machining trace of the wire electric discharge machine, so that any means for mutually relating them are not provided. In the conventional technique, therefore, it is not possible to display the workpiece shape and the actual machining trace at the same time and visually check whether or not the machining operation being performed is appropriate for machining the workpiece. It is also impossible to monitor the machining status on a monitor or another external device, because there is no means by which the external device can directly obtain positional information from the wire electric discharge machine.
One existing problem has therefore been that, although a machining trace can be depicted on the wire electric discharge machine from the current position status, enabling the trace to be visually checked, the shape of the workpiece cannot be displayed in this visual check.
In addition, the machining trace depends on various settings of the wire electric discharge machine, such as an offset setting and a corner radius-of-curvature setting, so the machining trace does not always match the contours of the target workpiece shape. From only the visual check of the machining trace on the wire electric discharge machine, therefore, it is not possible to tell whether the workpiece is being machined to the target shape.
Japanese Patent Applications Laid-Open 2002-268716, 2000-132214, and 2000-132222 disclose monitoring schemes in which machine screens displaying machining traces are displayed and monitored on a remote external device rather than being displayed at the wire electric discharge machine as described above.
The remote monitoring/control apparatus of the NC machining apparatus disclosed in Japanese Patent Application Laid-Open 2002-268716 has multiple systems 130a, 130b, 130c each including a server personal computer (PC) 110 as well as a machining apparatus 120 and NC controller 121, as shown in FIG. 12B; each server PC 110 receives coordinate axis data output from the control axes of the machining apparatus 120; a client PC 100 receives this data from the server PC 110, thereby enabling remote monitoring and remote control.
In Japanese Patent Application Laid-Opens 2000-132214 and 2000-132222, the server PC is operable as a Web server and its Web server functions are used for remote monitoring and remote control.
In the above conventional configuration having a server PC on the machining apparatus side, a problem is that a server PC is required for each machining apparatus. In the above conventional configurations using Web server functions, depicting on the external device depends on the depicting functions of the machining apparatus, so depicting functions such as zooming, scaling, and changing the point of view are restricted.